Rewilding: How a herd of bison reintroduced to Romania is helping ‘supercharge’ carbon removal

Rewilding: How a herd of bison reintroduced to Romania is helping ‘supercharge’ carbon removal

170 European Bison reintroduced to Romania’s Țarcu mountains could help capture and store the carbon released by up to 84,000 average US petrol cars each year.

New research from Yale University, which has not yet been peer-reviewed, suggests these massive herbivores could have a role to play in mitigating the impact of climate change.

By grazing a 48 square kilometre area of grassland in a wider landscape of 300 kilometres squared, they helped to capture an additional 54,000 tonnes of carbon each year. That is around 10 times the amount that would be captured by the ecosystem without the bison.

The report’s authors note, however, that this figure could be up to 55 per cent higher or lower. The higher figure is the equivalent of around 84,000 US petrol cars annually and the median average is 43,000 cars.

They do this through a combination of evenly grazing grasslands, recycling nutrients which fertilise the soil, dispersing seeds and compacting the soil to prevent carbon from being released. Researchers say that, having evolved alongside this ecosystem for millions of years, their removal has upset the delicate balance, causing carbon to be released.

“These astonishing results show the potential for reintroduced wild animals to supercharge the ability of ecosystems to draw down atmospheric carbon,” says Maheen Khan, climate lead for WWF Netherlands.

The organisation supported the study by WWF Romania, Yale University and the Global Rewilding Alliance together with Rewilding Europe.

“Rewilding in this way is now clearly a major option for policymakers in the face of rapidly accelerating climate change.”

Reintroducing bison to Romania after 200 years

European Bison were almost wiped out across the continent by rampant hunting between the 17th and 19th centuries.

By 1900 just two populations were left in the wild: one in the Białowieża Forest bordering Belarus and Poland, and one in the western Caucasus mountains running along Russia’s southern border with Georgia. These two herds were gone by 1927 with the species clinging to survival in a handful of European zoos.

After disappearing from Romania more than 200 years ago, Rewilding Europe and WWF Romania reintroduced bison to the Carpathian mountains in 2014. It is one of a number of successful reintroduction projects that are helping the large herbivores to make a comeback.

In total around 7,000 bison are now free-ranging across Poland, Lithuania, Russia, Ukraine and Slovakia.

The number of bison in Romania’s Țarcu mountains has risen to 170 individuals since reintroduction - one of the largest free-roaming bison herds in Europe.

European Bison in Białowieża Forest, Poland.
European Bison in Białowieża Forest, Poland. - Getty via Canva

Estimating the climate impact of rewilding

A new computer model was developed by scientists at Yale School of the Environment in the US to help calculate the exact amount of atmospheric CO2 that wildlife species help to capture and store. This research has been peer-reviewed and published in the Journal of Geophysical Research: Biogeosciences.

The Global Rewilding Alliance has been working with Yale University for three years to develop new methods of predicting the additional carbon captured if a landscape or seascape were rewilded.

In particular, they have focused on the reintroduction of animal species. The goal is to create a credible scientific basis for how rewilding can not only benefit wildlife and local communities but also address the wider climate crisis.

Each landscape and species is unique, however, and the effect of the European Bison is not likely to be the same for all rewilding scenarios.

The model uses information from fieldwork about the different ways that animals can affect the uptake and storage of carbon in ecosystems. Analysis shows that the presence of animals fundamentally changes relationships between microbes, plants and the environment.

That, in turn, leads to changes in the amount of carbon these ecosystems can capture and store.

“Our work reveals that wild animals could substantially increase an ecosystem’s carbon budget by 60-90 per cent, and sometimes even more, relative to cases where those animals are absent,” says Professor Oswald Schmitz from the Yale School of Environment, lead author of the report and developer of the model.

“This could potentially protect and enhance ecosystem carbon capture and storage globally by at least 6.4 billion tonnes per year. This amount rivals each of the IPCC’s top five steps for reducing net emissions expeditiously, including a rapid transition to solar and wind technology.”

The team is now working with partners in the Global Rewilding Alliance to apply the model around the world with the bison study providing the first results of this work.